.expand-transition(@transition, @height, @padding, @bgColor){
  transition: @transition;
  height: @height;
  padding: @padding;
  background-color: @bgColor;
  overflow: hidden;
}
.staggered-transition(@transition, @height, @margin){
  transition: @transition;
  height: @height;
  margin: @margin;
  overflow: hidden;
}